Natural Phenomenon: Topography

Details

The British Solomon Islands Protectorate had the largest land area of all British territories in the Pacific, except for British New Guinea (later Australian Papua). The scattered archipelago stretches about 1,448 kilometres southeast from Bougainville (q.v.). The Protectorate's major islands form a double chain south of Bougainville (part of the Solomon Archipelago but politically in Papua New Guinea) and converge again at Makira. The six main islands-Choiseul, New Georgia, Isabel, Guadalcanal, Malaita and Makira-are rugged and vary from 150 to 190 kilometres in length and 30 to 50 in width. The Protectorate included around nine hundred islands in all, with a total land area of 5,302 square kilometres.

The large islands have mountainous spines that typically drop on one side down steeply to sea level and on the other descend through a series of foothills to the coast. Mt. Popomanaseu (2,330 metres) on Guadalcanal and visible from Honiara was long thought to be the highest mountain, but a more accurate survey found the highest peak to be Mt. Makarakomburu (2,447 metres) on the Weathercoast at the head of the magnificent Koloula River. The northeast coast of Guadalcanal also has the largest coastal plain in the Solomons. Except for coral atolls and raised coral reefs, the cores of the main islands are of igneous and metamorphic rocks overlaid with a considerable thickness of marine sediments. The more recent emergence of these islands has in parts overlaid these rocks with spectacular level-topped terraces of coral reef rock.

There are extensive coral reefs and lagoons around many sections of the islands. Some parts of the coasts of the larger islands are deeply indented, providing sheltered harbours and anchorages. Ontong Java Atoll, to the north of the main island chain, and Sikaiana Atoll (Stewart Islands) to the northeast are typical large atolls. They, along with the raised atolls of Rennell and Bellona in the south and Tikopia and Anuta in the east, are the homes of most of the Protectorate's Polynesian communities.

Rivers are abundant on all of the large islands. They typically have steep courses for most of their length, and some are tidal near the coast, but only a few of the tidal reaches are navigable. In limestone areas the rivers tend to disappear and flow through underground caverns for long distances.

Because the Solomon Islands is part of the Pacific 'Ring of Fire', seismic activity (q.v.) is frequent, but volcanic activity is not as great as in Bougainville or the Bismarck Archipelago to the northeast. Tinakula (q.v.) near Santa Cruz is known to have been active for over four hundred years. Savo, opposite Honiara on Guadalcanal has not erupted since the nineteenth century but is potentially dangerous. Two submarine volcanoes erupt occasionally in the New Georgia Islands. (AR 1959-1960, 60-81)

Related entries

Published resources

Reports

• British Solomon Islands Protectorate, British Solomon Islands Protectorate Annual Reports (AR), 1896-1973. Details